Proper examination of X-ray films requires specific knowledge regarding the orientation of the X-ray film and the patient during exposure to an X-ray source. Certain patient positioning information is frequently embedded in radiographic images by placing a radio-opaque marker on the film or cassette prior to exposure. Two of the most common annotations are sidedness (e.g., left or right) and patient position (e.g., upright, supine, or decubitus). Gathering this type of information enables the proper analysis of X-ray films. For example, knowledge of the proper alignment of a patient in an upright position becomes critical for the detection of small amounts of free intra-abdominal air, an important indicator of gastrointestinal perforation.
X-ray opaque markers have been used for decades to permanently attach patient information to X-ray images. However, currently available X-ray opaque markers are deficient in multiple regards. For example, a commonly used position marker uses three tiny metal balls inside a small plastic globe. When exposed in the upright position, the balls fall to the bottom of the sphere. When exposed in the supine position, the balls are in the center of the sphere. However, this device does a poor job at communicating the range of positions from upright to supine, for example, because the ball movement is often inconsistent. Furthermore, this device describes only the position of the cassette and tells nothing of the relationship of the X-ray beam to the cassette. This device is also subject to damage and distortion of the outer plastic globe leading to poor mobility of the balls and a distorted characterization of position.
Other commercially available markers usually involve the assembly of individual letters onto a letter mount. These markers are costly to produce as they require the production of many individual pieces, and are time consuming to use because the letters or numbers or other indicia must be individually set up for each use. The most common markers are the two-piece, left and right marker that may include the technician's name or number. These markers are individually and temporarily secured to the film cassette when in use by tape. This requires the technician to carry messy tape and often results in the loss of the small markers. These markers provide no information regarding patient position at the time the X-ray is taken.
What is needed is a marker which more accurately describes the orientation of the cassette in relation to the X-ray beam, thereby effectively communicating patient position throughout the range of upright to supine, and which is durable and not prone to damage.